feat(mac): add agent events debug window

apps/macos/Sources/Clawdis/AgentEventStore.swift

@@ -0,0 +1,20 @@
+import Foundation
+
+@MainActor
+final class AgentEventStore: ObservableObject {
+    static let shared = AgentEventStore()
+
+    @Published private(set) var events: [ControlAgentEvent] = []
+    private let maxEvents = 400
+
+    func append(_ event: ControlAgentEvent) {
+        self.events.append(event)
+        if self.events.count > maxEvents {
+            self.events.removeFirst(self.events.count - maxEvents)
+        }
+    }
+
+    func clear() {
+        self.events.removeAll()
+    }
+}